It is required to prepare 1 kg of a 15% ammonia solution from a 25% solution.

It is required to prepare 1 kg of a 15% ammonia solution from a 25% solution. How many grams of a 25% ammonia solution and water do you need to take?

Given:
m2 solution (ammonia) = 1 kg = 1000 g
ω2 (ammonia) = 15%
ω1 (ammonia) = 25%

To find:
m1 solution (ammonia) -?
m (water) -?

Decision:
1) m2 (ammonia) = ω2 (ammonia) * m2 solution (ammonia) / 100% = 15% * 1000/100% = 150 g;
2) m1 (ammonia) = m2 (ammonia) = 150 g;
3) m1 solution (ammonia) = m1 (ammonia) * 100% / ω1 (ammonia) = 150 * 100% / 25% = 600 g;
4) m (water) = m2 solution (ammonia) – m1 solution (ammonia) = 1000 – 600 = 400 g.

Answer: The mass of the initial ammonia solution is 600 g; mass of water – 400 g.